A solenoid valve is an electrically controlled valve. The valve features a solenoid, which is an electric coil with a movable ferromagnetic core (plunger) in its center. In the rest position, the plunger closes off a small orifice. An electric current through the coil creates a magnetic field. The magnetic field exerts an upwards force on the plunger opening the orifice. This is the basic principle that is used to open and close solenoid valves.
NORMALLY CLOSED SOLENOID VALVE
For a normally closed solenoid valve, the valve is closed when de-energized and the media cannot flow through it. When current is sent to the coil, it creates an electromagnetic field that forces the plunger upwards overcoming the spring force. This unseats the seal and opens the orifice allowing the media the flow through the valve.
Two-port (2/2-way) Normally Closed brass electric solenoid valves are general purpose for controlling flow of air, water and oil with DC 12 Volt, DC 24 Volt, AC 110 Volt, AC 220 Volt. The NC valve is open when the solenoid is energized and it is closed when de-energized. It is widely used in the areas like mechanical, textile, medical, food processing and so on.
Normally Open Solenoid Valve
For a normally open solenoid valve, the valve is open when de-energized and the media can flow through it. When current is sent to the coil, it creates an electromagnetic field that forces the plunger downwards overcoming the spring force. The seal is then seating in the orifice and closing it, which prevents media from flowing through the valve. Figure 6 shows the operating principle of a normally open solenoid valve in the de-energized and energized states.
A normally open solenoid valve is ideal for applications that require the valve to be open for long periods of time as this is then more energy efficient.Suitable for use with hot or cold water, gas, air, very low viscosity fluids (< 20 cst), oils and hydrocarbons, e.g., gasoline, kerosene, or diesel fue
BI STABLE SOLENOID VALVE
A bi-stable or latching solenoid valve can be switched by a momentary power supply. It will then stay in that position with no power. Therefore, it is not normally open or normally closed as it stays in the current position when no power is applied. They accomplish this by using permanent magnets, rather than a spring.
They provide effective on/off control of water services ranging from 0.2 – 10bar where a constant supply of electrical power is either not appropriate or available. The range is available with the following approvals : WRAS , NSF , & UL/CSA
DIRECT ACTING SOLENOID VALVE
Direct acting solenoid are independent of the incoming water pressure using a diaphragm directly linked to the armature. When the coil is energised the armature lifts the seal from valve orifice thus allowing flow through the valve. They are supplied normally closed and provide effective on/off control of the liquid under low pressure applications typically less than 0.2 bar.
The range is available with the following approvals : WRAS , NSF , UL/CSA and ENEC